Stability Stressors in Electrocatalysis: Mechanistic Origins and Mitigation Strategies for Durable ORR Catalysts

The stability of electrocatalysts is a significant obstacle hindering the extensive implementation of proton exchange membrane water electrolyzers (PEMWEs) and fuel cells, especially under the severe acidic and high-potential operational conditions necessary for industrial use. Despite considerable advancements in catalytic activity, long-term durability remains undermined by various interrelated stability stresses. This review offers a thorough and mechanistic examination of the principal degradation pathways in electrocatalysis, emphasizing proton-exchange-membrane systems. Critical stability stressors such as active-site demetallation, corrosion of carbon support, and radical chemistry generated by hydrogen peroxide are methodically examined from both catalyst-centric and environment-mediated viewpoints. Recent advancements in operando characterization and theoretical modeling are emphasized to clarify the dynamic progression of active sites and the intricate interrelation of chemical, structural, and electrochemical degradation processes. Additionally, novel strategies to alleviate these stressors are thoroughly examined, including electronic structure modulation, second-shell and multi-atom coordination engineering, heterostructure and hybrid catalyst design, radical scavenging, spillover control, and electrolyte-mediated stabilization. This review delineates practical strategies for creating highly active, durable, and scalable electrocatalysts by merging mechanistic insights with rational materials design concepts. The insights provided here seek to facilitate future catalyst innovation and expedite the commercialization of sustainable hydrogen and fuel cell systems.